From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933551Ab2BBW2b (ORCPT ); Thu, 2 Feb 2012 17:28:31 -0500 Received: from mail4.aviatnet.com ([192.147.115.31]:51997 "EHLO mail4.aviatnet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932556Ab2BBW2a (ORCPT ); Thu, 2 Feb 2012 17:28:30 -0500 Subject: Re: [PATCH v3] rtc: ds1307: generalise ram size and offset From: Austin Boyle To: Wolfram Sang CC: , In-Reply-To: <1328143057.3159.34.camel@pc786-ubu.gnet.global.vpn> References: <1326144071.3096.25.camel@pc786-ubu.gnet.global.vpn> <20120111110650.GC2605@pengutronix.de> <1326320516.3096.64.camel@pc786-ubu.gnet.global.vpn> <20120119194541.GA32483@pengutronix.de> <1328143057.3159.34.camel@pc786-ubu.gnet.global.vpn> Content-Type: text/plain; charset="UTF-8" Date: Fri, 3 Feb 2012 11:28:24 +1300 Message-ID: <1328221704.3159.50.camel@pc786-ubu.gnet.global.vpn> MIME-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.16.1.34] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Wolfram, I have been thinking about this some more but maybe I don't understand the problem... > > ... that nvram is static and we are changing it. Yeah, it is very unlikely but > > if we have two RTC with different nvram sizes, one of them will not work correctly. > I see the issue. Am I right that it would only occur when you have two > I2C buses, each with one of the RTC chips supported by this driver? On my system, it looks like each rtc would have it's own directory e.g.: # ls /sys/class/rtc rtc0 # cat /sys/class/rtc/rtc0/device/name ds1388 # ls /sys/class/rtc/rtc0/device/ driver modalias name nvram rtc subsystem uevent So if you have multiple RTCs, even of the same type, they would be in rtc0, rtc1, rtc2 Since they each have their own nvram, does it matter if the size is changed? Cheers, Austin.